bf1 expansions

1. GC generation assumes that the life cycle of most objects is short and survival time is short. So the first thing that the GC algorithm focuses on is these short-lived objects. For applications with low load, the FULLGC phenomenon will not occur. This reminds us that we should shorten the life cycle of the object as much as possible. Some programmers reduce the number of new objects as much as possible, try to reduce the allocation overhead of the heap, and reduce memory fragmentation, but th

a . PrefaceThe consistent hash (consistent Hashing), first proposed by MIT's Karger in 1997, is primarily used to address the service shocks caused by outages and expansions in volatile distributed web systems. Now the idea of the algorithm has been widely used, and in practice has been a great development.two . Algorithm Design1. Source of the problemA service consisting of 6 servers, each server responsible for storing 1/6 of the data, and when the

sets, 5 class layout reduced to 3 after optimization. Risk control Risk: 6 years of products, old user habits, loyal users of the small nest version of the preference, dead IE6 Control ideas: Old user habits-improve the upgrade strategy to provide the old version of the transition period, early beta Loyal users-upgrade version compatibility, provide a small nest version of the alternative and a richer version of the scene IE6 drag-Browser effect differentiation, boot upgrade browser Refa

mobile phone companies, designed to bring value, including differentiated value, reduced risk, and why risk reduction? Because originally you need your research and development team to come out a product for half a year, the result is public do not like after the listing. But now it's only a few weeks from the design team that you'll be able to verify this thing, then you can have better iterations and expansions, such as a series of products you com

, open the project|. Options option. Project Options First we stop at the "Compiler" (compile) tab. You simply click the Full debug mode button, and the vast majority of the rest of the setup we need is done. It's always good to set code optimization to None (none), which actually tells the compiler that everything is done, just generate the machine code. Instead of trying to do other intelligent optimizations to improve the speed of a little bit of running. (Of course, after everything is don

, locks can be based on file name modification, temporary files; 5. Do not attempt to start with business considerations, you know, many times the business is accompanied by the growth of the system and mature. In the early stages of design and implementation, too much effort is likely to become unproductive. You should focus your design on the different business expansions. 6. Using polling is sometimes a wise way to reduce system coupling to a gre

contrast to the implementation of Stingbuffer and StringBuilder other details, take the Append () method as an example. Public synchronized StringBuffer append (String str) { super.append (str); return this; } Public StringBuilder append (String str) { super.append (str); return this; }The biggest difference between the two is: Stingbuffer all the methods of implementation are sychronized modified, StringBuilder is not. Summary of 2.String, Stri

Thanks a lot, http://blog.csdn.net/drifterj/article/details/7814536. As the application needs to deal with the exponential expansion of data volume and analyze the expansion of this massive data demand, the relational database is gradually showing a fatigue state. When the system is scaled horizontally, the relational database often becomes the bottleneck of performance improvement. At this point, NoSQL technology became the initiator and winner of the change. MongoDB is the most powerful one

portal, strengthen privacy permissions, global settings and personal data, dress up template 46 set to optimize the 20 sets, 5 class layout reduced to 3 after optimization. Risk control Risk: 6 years of products, old user habits, loyal users of the small nest version of the preference, dead IE6 Control ideas: Old user habits-improve the upgrade strategy to provide the old version of the transition period, early beta Loyal users-upgrade version compatibility, provide a small nest version of

Hessian matrix, translated black plug matrices, Haisen matrices, Heather Matrix, sea plug matrix and so on. is a square of the second derivative of a multivariate function, and describes the local curvature of the function. The Hessian matrix was first proposed by the German mathematician Ludwig Otto Hesse in 19th century and named after its name. Hessian matrix is commonly used to solve the optimization problem by Newton Method , and the Hessian matrix can determine the extremum problem of mult

the InnoDB engine's database allocates compute-and-memory physical machines for business situations, or hybrid, and can consider using Redis for partial storage to mitigate database stress.Advantages and disadvantages of vertical splitting:Advantages:1) by single-Library single-table split into multi-Library multi-table, reducing the database additions and deletions to check the pressure2) to split the hot and cold data, reduce the cost and reasonable use of hardware3) for a vertically split da

problem is that the method is not scalable enough. The reason is that there may be many fields in the formal table, and the types of these fields vary widely. If you later add a new feature that requires modification approval for some of the formal table's fields, the current temporary table will not be satisfied. Because the temporary table is the primary key of the ID, if you continue to use the temporary table, the previous approval results cannot be saved. To accommodate future

avoid loading too much data when scanning with cluster index (clustered index) when accessing data, or to lock or lock too long when data is modified. ----------------------------------------------------- 5, Image Server separation For Web server, the user requests for pictures are the most consuming system resources, so the size of the Web site and the characteristics of the project, the deployment of a separate picture server, and even multiple picture servers. ------------------------------

Tags: dynamic join good TPS user support data redundancy lock table growthField extension scheme for database tables Traditional SolutionsI. Reserved fieldsA reserved field is a pre-set field for subsequent business expansions at the beginning of the database table design, for exampleAt the beginning of the design, the user table is uid,name,col1,col2,col3. You can try the reservation field directly when you need to extend the field.Advantages1. New N

The premise is that MySQL is installed, Setuptools is installed, and then refer to Web http://jingyan.baidu.com/article/fedf07377ded3e35ad897750.html to associate MySQL with Django. This makes it possible to associate the model with the database in Django.If you don't use a Django module, here's a simple introduction to Python's MySQLdb module. The reference http://www.cnblogs.com/rollenholt/archive/2012/05/29/2524327.html is based on a small number of deletions and

January 18, 2012, Amazon released Amazondynamodb, a fully managed, high-performance, high-reliability, cost-effective NoSQL database. Dynamodb is ideal for Internet-scale applications.The DYNAMODB database incorporates Amazon's many years of experience in large, non-relational databases and cloud computing. As early as 2007, Amazon published a paper that delves into the design concepts and implementation technologies used by Amazon Dynamo, and how to solve large scale

DBMS and is widely used as a tool in database design for data modeling. The E-R data model has undergone many modifications and expansions since its inception. Let's look at a simple ER diagram, as shown below:In our ER diagram, what is the meaning of each figure? NIE, the small part to introduce briefly, the ellipse represents the attribute. Rectangular means the entity, diamond means contact, the number indicates the type of contact, such as wareho